Efficacy of Escherichia coli O157:H7 Siderophore Receptor/Porin Proteins–Based Vaccine in Feedlot Cattle Naturally Shedding E. coli O157

Abstract Escherichia coli O157 is a foodborne pathogen commonly isolated from beef cattle feces and can enter the food chain at harvest. A relatively new vaccine technology uses the iron requirement of pathogenic bacteria by targeting the siderophore receptor and porin proteins (SRP). We evaluated the efficacy of an anti–E. coli O157 SRP-based vaccine in feedlot cattle naturally shedding the organism. Sixty cattle were selected from an original population of 600; 50 of these were fecal positive for E. coli O157 on two occasions and the remaining 10 animals were fecal positive on one occasion. Cattle were stratified based on the results of screening samples and randomly allotted to one of three treatment groups: control, vaccinated with 2 mL per animal of E. coli SRP vaccine, or vaccinated with 3 mL per animal of E. coli SRP vaccine subcutaneously 21 days apart. Control cattle were injected with sterile saline emulsified with an adjuvant. Fecal samples and rectoanal mucosal swab samples were collected two ...